Re: [PATCH v2 03/10] make qdev_disconnect_gpio_out_named() public

[lixianglai]

Hi Philippe Mathieu-Daudé :
> Hi,
>
> On 12/9/23 04:11, xianglai li wrote:
> > It will be reused in loongarch/virt.c for unwiring
> > the vcpu<->exioi interrupts for the vcpu hot-(un)plug
> > cases.
>
> Since we never had to use this, I'm surprised we really need it.
>
> QEMU IRQs/GPIOs are similar to hardware ones, and aren't expected
> to be rewired at runtime. Usually another hot-pluggable bus layer is
> used, and the bus is physically wired toward the hardware.
>
>
> I suppose you want to add that because a unplugged vCPU is still
> receiving IRQs. The question is, why? Before unplugging, I expect
> the INTC (IPI) here to be signaled a vCPU is going to be unplugged,
> so maybe you are missing handling the unplug event there. See


I did not receive an interrupt signal after pulling out the vcpu.

Whether to use the qdev_disconnect_gpio_out_named function does not 
affect the cpu hot swap function.

The qdev_disconnect_gpio_out_named function is used only to make

loongarch_cpu_irq_init and loongarch_cpu_irq_uninit symmetrical.

I thought it would make the whole process more regular and nice.

If this causes confusion I think with the next patch I can remove the 
reference to this function.

Thanks,

xianglai.


> in loongarch_ipi_writel():
>
>     switch (addr) {
>     case CORE_EN_OFF:
>         s->en = val;
>         break;
>     case CORE_SET_OFF:
>         s->status |= val;
>         if (s->status != 0 && (s->status & s->en) != 0) {
>             qemu_irq_raise(s->irq);
>         }
>         break;
>     case CORE_CLEAR_OFF:
>         s->status &= ~val;
>         if (s->status == 0 && s->en != 0) {
>             qemu_irq_lower(s->irq);
>         }
>         break;
>
> Maybe you need to factor ipi_raise/lower() helpers which check cores
> are available & enabled before propagating IRQ?
>
> > Co-authored-by: "Salil Mehta" <salil.mehta@opnsrc.net>
> > Cc: "Salil Mehta" <salil.mehta@opnsrc.net>
> > Cc: Xiaojuan Yang <yangxiaojuan@loongson.cn>
> > Cc: Song Gao <gaosong@loongson.cn>
> > Cc: "Michael S. Tsirkin" <mst@redhat.com>
> > Cc: Igor Mammedov <imammedo@redhat.com>
> > Cc: Ani Sinha <anisinha@redhat.com>
> > Cc: Paolo Bonzini <pbonzini@redhat.com>
> > Cc: Richard Henderson <richard.henderson@linaro.org>
> > Cc: Eduardo Habkost <eduardo@habkost.net>
> > Cc: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
> > Cc: "Philippe Mathieu-Daudé" <philmd@linaro.org>
> > Cc: Yanan Wang <wangyanan55@huawei.com>
> > Cc: "Daniel P. Berrangé" <berrange@redhat.com>
> > Cc: Peter Xu <peterx@redhat.com>
> > Cc: David Hildenbrand <david@redhat.com>
> > Cc: Bibo Mao <maobibo@loongson.cn>
> > Signed-off-by: xianglai li <lixianglai@loongson.cn>
> > ---
> >   hw/core/gpio.c         | 4 ++--
> >   include/hw/qdev-core.h | 2 ++
> >   2 files changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/hw/core/gpio.c b/hw/core/gpio.c
> > index 80d07a6ec9..4fc6409545 100644
> > --- a/hw/core/gpio.c
> > +++ b/hw/core/gpio.c
> > @@ -143,8 +143,8 @@ qemu_irq qdev_get_gpio_out_connector(DeviceState 
> > *dev, const char *name, int n)
> >     /* disconnect a GPIO output, returning the disconnected input (if 
> > any) */
> >   -static qemu_irq qdev_disconnect_gpio_out_named(DeviceState *dev,
> > -                                               const char *name, int n)
> > +qemu_irq qdev_disconnect_gpio_out_named(DeviceState *dev,
> > +                                        const char *name, int n)
> >   {
> >       char *propname = g_strdup_printf("%s[%d]",
> >                                        name ? name : 
> > "unnamed-gpio-out", n);
> > diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
> > index 151d968238..32bb54163e 100644
> > --- a/include/hw/qdev-core.h
> > +++ b/include/hw/qdev-core.h
> > @@ -739,6 +739,8 @@ qemu_irq qdev_get_gpio_out_connector(DeviceState 
> > *dev, const char *name, int n);
> >    */
> >   qemu_irq qdev_intercept_gpio_out(DeviceState *dev, qemu_irq icpt,
> >                                    const char *name, int n);
> > +qemu_irq qdev_disconnect_gpio_out_named(DeviceState *dev,
> > +                                        const char *name, int n);
> >     BusState *qdev_get_child_bus(DeviceState *dev, const char *name);